The maintainers should probably just run their own git server as a hidden service, change their git name/email/signing keys and be done with it.
Going after youtube-dl so publicly has a solid Streisand effect. Feel as though the lawyers aren't going to give up easily on this one and will hound them one way or another.
Regardless, there is some github alternatives available through tor:
Darktea: http://it7otdanqu7ktntxzm427cba6i53w6wlanlh23v5i3siqmos47pzh...
Rootgit: http://rootgit4rghbuenb.onion/explore/repos
And on I2P: